Circuit breakers provide automatic power interruption to an electrical load when fault conditions occur, such as an overload current or a short circuit. A circuit breaker is typically deployed on a line conductor between a load and a current source, usually an electric main. The current source provides current over the line conductor through the circuit breaker and to the load, which is typically also connected to ground or neutral. A neutral conductor provides a return path from the load through the circuit breaker and back to the current source.
A typical circuit breaker has a load terminal for connecting the circuit breaker to the load and a line terminal for connecting the circuit breaker to the line conductor. A braided wire conductor carries current from the line terminal to one side of a trip unit. The other side of the trip unit is connected to the load terminal by an electrical contact that provides a path for current to flow through the circuit breaker. The trip unit typically includes an armature having an opening therein for engaging and holding a latch of the trip unit. During normal operation, the armature remains in the latched position and current is allowed to flow through the circuit breaker. When a fault condition occurs, the armature is moved to the unlatched position, tripping the circuit breaker and interrupting the flow of current.
In most residential and commercial establishments, the circuit breakers are installed in a circuit breaker panel that serves as a central distribution point for the various loads in the establishments. The circuit breaker panel typically has a plurality of compartments and the circuit breakers are plugged or otherwise installed in the panel by pressing or inserting them into the compartments. Each compartment typically includes a bracket, guides, openings, and/or other means for receiving and engaging the circuit breaker.
Occasionally, it may be necessary to unplug a circuit breaker from the circuit breaker panel. For example, the circuit breaker may need to be removed for servicing or maintenance, or it may need to be replaced with another circuit breaker with a different current rating due to new load requirements. Preferably the circuit breaker panel is de-energized before the circuit breaker is removed, but in some situations it is not feasible to de-energize the panel. In these situations, it is prudent to ensure the circuit breaker is in the tripped state so current is not flowing at the time the circuit breaker is removed from the panel. If the circuit breaker is inadvertently removed while current is flowing, arcing may occur, potentially leading to electrical shock, arc flash, load damage, or other hazardous event. For the same reasons, it is equally important to ensure the circuit breaker is in the tripped state during installation so the circuit breaker is not inadvertently plugged in while current is able to immediately flow through it.
Accordingly, a need exists for an improved circuit breaker that addresses the above and other problems, and particularly a circuit breaker with a mechanism that prevents the circuit breaker from being inadvertently installed or removed while current can immediately flow or is flowing through the circuit breaker.